The present invention is a deposition prevention method of coking deposits using a turbocharger (120) including a turbine (122) including a flow path section having a vane section, a nozzle, and a housing, and a compressor (124) configured to introduce air into an engine (110) using rotation of the vane section of the turbine, and installed at an exhaust path (202) of the engine. The method includes a film coating process of forming a film including an element having a standard free energy change in a carbonization reaction of −50 kJ/mol or more on at least one surface of the vane section, the nozzle and the housing of the flow path section of the turbine.